Washing machine appliances generally include a cabinet that receives a tub for containing wash and rinse water. A wash basket is rotatably mounted within the wash tub. A drive assembly is coupled to the wash tub and configured to rotate the wash basket within the wash tub in order to cleanse articles within the wash basket. Upon completion of a wash cycle, a pump assembly can be used to rinse and drain soiled water to a draining system.
Washing machine appliances include vertical axis washing machine appliances and horizontal axis washing machine appliances, where “vertical axis” and “horizontal axis” refer to the axis of rotation of the wash basket within the wash tub. Vertical axis washing machine appliances typically have the wash tub suspended in the cabinet with suspension devices. The suspension devices generally allow the tub to move relative to the cabinet during operation of the washing machine appliance.
A significant concern during operation of washing machine appliances is the balance of the tub during operation. For example, articles loaded within a basket may not be equally weighted about a central axis of the basket and tub. Accordingly, when the basket rotates, in particular during a spin cycle, the imbalance in clothing weight may cause the basket to be out-of-balance within the tub, such that the central axis of the basket and tub move together in an orbital fashion. Such out-of-balance issues can cause the basket to contact the tub during rotation, and can further cause movement of the tub within the cabinet. Significant movement of the tub can cause the tub to contact the cabinet, potentially causing excessive noise, vibration and/or motion or causing damage to the appliance. Moreover, known methods fail to efficiently or accurately measure or account for displacement excursions.
Various methods are known for monitoring load balance of washing machine appliances. However, such methods typically monitor load balance and detect out-of-balance states during the spin cycle, when the basket is spinning at a high rate of speed. Accordingly, noise, vibration, movement or damage may occur despite the out-of-balance detection.
Accordingly, improved methods and apparatus for monitoring load balance in washing machine appliances are desired. In particular, methods and apparatus which provide accurate monitoring and detection at earlier times during the wash cycle would be advantageous.